1. Field of the Invention
The present invention relates to a vibrating gyroscope and an electronic unit including the same. More particularly, the present invention relates to a vibrating gyroscope used in a hand-shaking correction device for use in, for example, an automobile navigation system or a video camera, and to an electronic unit including the above-described vibrating gyroscope.
2. Description of the Related Art
A gyroscope is used for, for example, a hand-shaking correction device for use in an automobile navigation system or a video camera. One type of such a gyroscope is a vibrating gyroscope for detecting the angular velocity applied to a vibrator by detecting distortion of a bar-shaped bending-vibrating-type vibrator caused by the Coriolis force. In the vibrating gyroscope, the vibrator must be supported without interfering with the vibration of the vibrator. Japanese Unexamined Patent Application Publication No. 11-125526 discloses a structure for supporting a vibrator.
In the vibrating gyroscope disclosed in this publication, a bar-shaped vibrator having two main surfaces (first and second main surfaces) includes a pair of supporting members fixed to electrodes provided on the first and second main surfaces, respectively, in the vicinity of two node points of the vibration generated by driving. The supporting members extend from the first and second main surfaces of the vibrator in the widthwise direction of the vibrator. A bending portion having a component in the longitudinal direction of the vibrator is also provided between the portion of the supporting member fixed to the electrode and the end of the supporting member.
Thus, the supporting members do not substantially interfere with the vibration of the vibrator, the vibration of the vibrator does not substantially leak to the exterior.
However, in the vibrating gyroscope disclosed in the above-described publication, the positions of the supporting members are not aligned with the node axes. This configuration often interferes with the vibration of the vibrator. Accordingly, the vibration of the vibrator leaks to the exterior via the supporting members, and the vibration is unstable, thereby decreasing the detection precision of the angular velocity.
In order to overcome the above-described problems, preferred embodiments of the present invention provide a vibrating gyroscope which does not interfere with the vibration of a vibrator, and an electronic unit including such a novel vibrating gyroscope.
A preferred embodiment of the present invention provides a vibrating gyroscope including a bar-shaped vibrator for performing double-end-free bending vibration in the thickness direction according to a drive signal, and a pair of supporting members securely provided and aligned with two node axes of the vibrator on both sides of the vibrator in the thickness direction. The pair of supporting members extend from positions at which the supporting members are fixed to the vibrator in the widthwise direction of the vibrator, and include bending portions which bend toward each of the node axes, and a proximity portion at which the pair of supporting members are in close proximity with each other with a gap provided in the vicinity of the corresponding node axis.
In the aforementioned vibrating gyroscope, the pair of supporting members preferably extend substantially parallel to the widthwise direction of the vibrator with the gap provided at the proximity portion.
In another preferred embodiment of the present invention, the pair of supporting members intersect with each other with the gap provided at the proximity portion.
In another preferred embodiment of the present invention, the pair of supporting members include extending portions that extend in the longitudinal direction of the vibrator via the bending portions and the proximity portion from the locations at which the pair of supporting members are fixed to the vibrator.
The minimum gap between the pair of supporting members at the proximity portion is preferably about one half or less than the thickness of the vibrator.
At the proximity portion, the gap between one of the pair of supporting members and the node axis is preferably substantially equal to the gap between the other supporting member and the node axis.
The vibrator preferably includes a first main surface and a second main surface extending in the thickness direction, electrodes provided on the first main surface and the second main surface, and the pair of supporting members being fixed to the electrodes.
In the vibrating gyroscope according to preferred embodiments of the present invention, the vibrator is preferably supported by the supporting members at the node axes. Thus, the leakage of the vibration of the vibrator to the exterior is greatly decreased, and the vibration is stable, thereby greatly improving the detection precision of the angular velocity.
An electronic unit according to another preferred embodiment of the present invention includes the vibrating gyroscope according to preferred embodiments described above.
The performance of the electronic unit according to preferred embodiments of the present invention is greatly improved by including the vibrating gyroscope according to preferred embodiments of the present invention.
Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments with reference to the attached drawings.